Infectious diseases, such as AIDS and serum hepatitis, have created an urgent need for a reliable, practical and convenient anti-contaminating medical syringe. Such a syringe must be relatively inexpensive to manufacture, rendering it disposable after a single injection or usage.
The objective of the present invention is to fully satisfy the need for an anti-contaminating syringe in terms of fully protecting the patient, medical personnel and innocent third parties against the possibility of infection being transmitted by the syringe.
Toward this end, the syringe according to the present invention is provided in a sterile, easily openable package and is pre-adjusted so that it is ready to be used for injecting a patient after removal from the sterile package and after separation of a removable shield from the forward end of the syringe which encloses the syringe needle prior to use.
The syringe is operated conventionally to draw liquid medication from a bottle having an elastic diaphragm or stopper and to then inject the patient.
A housing element within which a piston head of the syringe plunger assembly is captured and which is locked to the forward end of the syringe barrel prior to and during normal usage of the syringe is unlocked by a twisting action of the plunger assembly and is then retracted with the plunger assembly toward the rear of the syringe barrel where such assembly, including the piston head housing, becomes automatically positively locked to effectively prevent reuse of the syringe. In this retracted position, the syringe needle is held inside of the barrel rearwardly of a safety shield on the forward end of the barrel containing an elastic membrane through which the needle projected prior to and during the injection process. The retracted needle cannot be touched nor can the membrane in the safety shield be touched, thus rendering the transmission of infection by the syringe virtually impossible.
Other features and advantages of the syringe according to the present invention will become apparent to those skilled in the art during the course of the following description.